Theory-building in drug abuse research can potentially benefit greatly from causal modeling, but currently available statistical methods for the causal analysis of correlational data require mathematical and computer skills that drug researchers typically do not have. This proposal develops and evaluates computer-interactive methods for building and testing theories of drug use and abuse. Various computer languages are evaluated for their relevance to interactive drug abuse model building. Thereafter, a series of interactive programs that can be combined into a single superordinate program are developed and evaluated for their ability to help drug abuse theory building. These programs implement the following tasks: generate and label path diagrams for measurement models; generate and label path diagrams for structural (causal) models; translate path diagrams into model specifications by equations; determine the identification of parameters in the causal model; generate equality and other constraints on parameters; generate starting values for methods of parameter estimation; and provide control and computer-input information for major general causal modeling computer programs such as LISREL. It is expected that these interactive methods can minimize the informational load required to implement causal modeling to such an extent that drug-abuse theory development and hypothesis testing can be significantly advanced.